One of the strongest risk factors for autoimmune diseases such as Multiple Sclerosis (MS) and Type 1 Diabetes (T1D) is how far away from the equator you live. Prevalence of MS ranges from 1-2/10,000 near the equator and
up to 200/10,000 at latitudes higher than 50 degrees. Studies show reductions in risk for MS:
- Higher sun exposure when aged 6 to 15 years in Tasmania
- Summer outdoor activities in childhood and adolescence in Norway
- Sun sensitive skin type 1 and 2 in the UK
- Higher oral vitamin D intake. Areas with diets rich in fish oil have lower incidence of MS
These studies suggest that greater sun exposure and/or greater dietary intake of vitamin D is protective against autoimmunity.
- A 30 year follow-up study in Finland found a marked reduction in the prevalence of type 1 diabetes (relative risk 0.12) in infants who received daily vitamin D supplementation in the 1960s.
- The presence of islet auto-antibodies in offspring was inversely correlated with maternal dietary vitamin D intake during pregnancy.
Vitamin D is not only beneficial for the prevention of autoimmunity, but if administered during the development of the disease it has the ability to block the progression of the disease.
